Unify TF-M and Mbed-SPM code generators:
- Unify SPM initialization logic:
- All partitions are registered at once
- Test partitions are guarded by #ifndef
- Introduce single template list
- Beatify template files and add "Autogen-do not modify" notice
Prepare for integration with mbed-os build system:
- Generate all the files in a single place
Simplify tools/psa/release.py script
* Unify PSA generators
* Replace scanning for mbed_spm templates with json
* Make generate_source_files and parse_manifests common
* Make assert_int an internal function
* Use parse_manifests in pytests
* Update docs